Field of the Invention
The following description relates to a conductive pattern making method and a conductive pattern, and more particularly, to a conductive pattern making method and a conductive pattern that is capable of easily adjusting the electrical characteristics and optical characteristics with improved process efficiency.
Description of Related Art
Recently, as various home appliances and communications apparatuses are becoming digitalized and show improved performance, together with the rapid expansion of the display field, a technology of forming a conductive transparent substrate having a low resistance and high transmissivity is gathering attention.
Such a conductive transparent substrate must be made of a material that is transparent but also has a low resistance, and that exhibits a high flexibility to provide mechanical stability. It must also have a similar coefficient of thermal expansion as that of the substrate, so as to prevent a device from being circuit-shorted and prevent a significant change in the sheet resistance, even when the device is overheated or is subject to a high temperature.
Suitable materials to be used in a conductive transparent substrate include metal oxides, CNT (carbon nanotube), graphene, high molecule conductor, and metal nano wire etc. Of these materials, ITO (indium tin oxide) is most frequently used to form a thin film layer in a vacuum method. However, ITO (indium tin oxide) is a ceramic material that has a low resistance to bending or curving of the substrate, and thus a crack can be easily formed and propagated, thereby deteriorating the characteristics of the electrode. Furthermore, activating through substitution of a tin dopant is difficult, and the defects of its amorphousness exhibit a high sheet resistance. Not only that, the cost of indium which is the main material of ITO continues to increase due to the rapid expansion of the flat panel display, mobile device, and touch panel markets, and the limited reserves of indium is deteriorating the price competitiveness of transparent conductive films. Therefore, in order to gain the upper hand in the display technology competition that is expected to be fierce in the years to come, it is very important to develop an alternative material that can resolve the aforementioned problems of an ITO electrode.
When using a polymer conductor to make a transparent conductive film, materials such as polyacetylene, polypyrrole, polyphenol, polyaniline, and PEDOT:PSS are used, but these polymer conductors have low solubility, are difficult to process, and emit colors when the energy gap is 3 eV or less. A substrate coated with a thin film in order to increase the transmissivity increases the sheet resistance, which may be a problem when using the substrate as a transparent electrode. Furthermore, most of the polymer conductors have a low atmospheric stability, and thus may be oxidized quickly in the atmosphere, thereby deteriorating the electrical conductivity. And thus, securing stability is also important.
Much research is being conducted on using CNT, graphene, and metal nano wire to manufacture a conductive transparent film, but there are many problems to be solved before using them in conductive transparent films having low resistance, and thus such research has not reached the step of commercialization yet.
Recently, in order to resolve the aforementioned problems, research is being conducted proactively in methods for forming a metal mesh type conductive transparent film using metals having excellent conductivity and mechanical strength. These methods include a method for forming fine engraved grooves using an imprinting method and filling them with metal, a method of directly etching a surface of a resin layer or a resin layer and a substrate simultaneously with laser to form fine grooves and filling the grooves with a metal layer, a method of coating a substrate with metal in a vacuum deposition or full coating method and then using a photo etching process, and a method of using a direct printing technique such as flexo, gravure, gravure offset, reverse offset, and inkjet printing etc.